Altera SerialLite II IP Core - Manual (Page 52)

Chapter 3: Parameter Settings 3–29
Optimizing the Implementation
January 2014 Altera Corporation SerialLite II MegaCore Function
User Guide
Error signals, such as txrdp_err and txhpp_err, are asserted by user logic. When
txrdp_err
is asserted with txrdp_eop, the packet is marked with the end of bad
packet (EBP) marker. The txrdp_err signal is ignored when it is not asserted with
txrdp_eop
.
When the txhpp_err is asserted and the Retry-on-error feature is turned off, the
packet is marked with the EBP marker. When the txhpp_err is asserted and the Retry-
on-error
feature is turned on, the packet is not transmitted and is silently dropped.
Optimizing the Implementation
There are a number of steps you can take to optimize your design, depending on your
goals. The features selected in your SerialLite II configuration have a substantial
impact on both resource utilization and performance. Because of the number of
different combinations of options that are available, it is difficult to generalize the
performance or resource requirements of a design. In addition, the performance of a
SerialLite II link in isolation is different from the performance of the same link
instantiated alongside large amounts of other logic in the device.
For the most part, the steps you take to improve performance or resource utilization
are similar to the steps you would take for any other design. The following
suggestions are intended to provide ideas, but should not be considered an
exhaustive list.
Improving Performance
Performance is the factor that depends most on what other logic exists in the device. If
the SerialLite II MegaCore function is competing with other logic for routing
resources, inefficient routing could compromise speed. The following sections
describe some things that can be considered if speed is an issue.
Data
■ Invalid 8b/10b codes groups
■ Running disparity errors
■ Unsupported valid code groups
■ Link protocol violation
■ LMP with BIP error
■ CRC error
■ Unexpected channel number
■ Out of order packet
■ Out of order acknowledgment (if retry-
on-error enabled)
Two possibilities:
■ If Retry-on-error is enabled
and the packet is a priority
packet, request
retransmission.
■ Otherwise, mark the packet as
bad and forward it to the user
link layer.
Packets Marked
Bad
{EBP} marked packet
Received packet is marked as bad
via the rxrdp_err or rxhpp_err
signals, and forwarded to the
user link layer.
Table 3–12. Error Summary (Part 2 of 2)
Error Type Cause Action